Surgical pad sterilizer



1944- F. M. MINER, JR I I 2,356,684

SURGICAL PAD STERILIZER Filed Oct. 25, 1941 I W I INVENTORV ATTORNEY Patented Aug. 22, 1944 SURGICAL PAD STERILIZER Frederick Mason Miner, Jr., Madison, Wis, as-

. si'gnor to Renim, Inc.

poration of Wisconsin Madison, Wis, "a cor- Application October 25, 1941, Serial No. 416,474

(Cl. 68f21) Claims.

This invention relates to apparatus for steril izing surgical pads and resides in an improved form thereof in which a basin for accommodating pads during sterilization is provided with a movable wall which is superimposed upon the pads and in which a boiler connected to said basin is arranged to drive fluid against atmospheric pressure into said sterilizer basin to sterilize the pads and after sterilization to receive said fluid back again while atmospheric pressure acts upon said movable wall to express the sterilizing fluid from said pads.

Heretofore, in sterilizers adapted for sterilization of surgical dressing pads by contact with liquid at the boiling point, a serious problem has been encountered in providing means for removing excess liquid from the pads to place them in useable condition.

When ordinary equipment is employed, the pads must be wrung in the open air with sterile forceps. This is a cumbersome and tedious procedure and one which is exasperatingly ineffective. The pads rapidly lose temperature and are of only limited usefulness for hot applications.

Apparatus has been proposed, to cope with this difficulty, in the form of a mechanical press, which is immersed with the pads into the sterilizer liquid and withdrawn therefrom together with the pads at the end of the sterilizing treatment. The liquid is then squeezed from the pads by the action of the press while the pads are in the open air. When the press is opened and the pads are taken therefrom, one by one, for use, the remaining pads rapidly lose temperature. To retain the temperature of the remaining pads, it is necessary to repeatedly reimmerse and rewring the same, which is a troublesome and annoying procedure. The apparatus required to handle the pads in this manner is, furthermore, complex and expensive.

In contrast with the above, the apparatus of this invention delivers the sterilized pads at the end of the sterilizing treatment in condition ready for immediate use and the pads may be removed from the sterilizer one by one, for use, without disturbing the remaining pads, which remain within the sterilizer basin protected from rapid loss of temperature.

This invention is herein described by reference to the accompanying drawing which forms a part hereof and in which there is set forth by way of illustration and. not of limitation a form of apparatus constructed in accordance with this invention.

In the drawing:

Fig; 1 is a front elevation partly in section of a sterilizer constructed in accordance with this invention;

Fig. 2 is a front elevation, with parts broken away, to show surgical pads when compressed at completion of sterilizing operation;

Fig. 3 is a fragmentary top view, partly in section, taken on line 33 of Fig. 1.

Referring to the drawing, a sterilizer constructed in accordance with this invention is shown. The sterilizer is made up of a body portion I, having a central boiler compartment I, which is tightly enclosed between the head plate IQ and the bottom plate 8. Beneath the bottom plate 8 a compartment 5 is provided for housing an electrical resistance heating unit 6. The unit 6 is secured to the plate 8 in contact with the under side thereof so that the heat from the unit 6 will be readily conducted to and through the plate 8. The bottom of compartment 5 is closed for convenience by a closing sheet 2|, which carries supporting feet 4, as shown.

Tightly secured in a central opening II in the head plate I0 is a dip pipe I2, which extends downwardly to a point in close proximity to the bottom of the boiler compartment I. Above the boiler compartment '1 is a sterilizer basin 9, formed by the upward extensions I4 of the side walls of the body I. The sterilizer basin 9 is thus in communication with the boiler compartment I, through the dip pipe I 2. In this way liquid at the boiling point will be driven from the boiler compartment 1 up the dip pipe I2 into the basin 9, when sufiicient heat is supplied through the element 8 to raise liquid contained in the boiler compartment 1 to the boiling point,

The basin 9 i conveniently formed in rectangular shape so that a plurality of squarefolded surgical pads 22 may be stacked in position, as shown in Fig. 1. With the pads 22 in position, a follower plate I3 is placed on top of the same, resting in a horizontal position with its edges in close proximity with the walls I4. As shown more indetail in Fig, 3, a small space exists between the. side edges of the plate I3 and the inner facesof the wall Hi. This permits the follower plate I 3 to move freely .a vertical direction and, further, to serve an important function in connection with the cycle of sterilizing treatment contemplated. This additional function will more clearly appear from the de scription of operation hereinafter set forth.

To provide means for filling and emptying the boiler compartment I and for controlling the liquid level therein, filler plug II, vapor outlet 25, gage-cock l8, and gage-glass I6 are provided. As indicated in outline, plug I! may be removed and a funnel may be placed in the opening provided therefor for filling. A cock 23 and spigot 24 are also provided to provide and control communication between the vapor space in boiler compartment I and the sterilizer basin 9, for a purpose more fully explained hereinafter.

In processing surgical pads to prepare the same for use, it is necessary not only that they be sterilized, but, also, that they be furnished hot and in a semimoist condition at the time of use. To effectively sterilize without resort to superatmospheric pressure, it is necessary to maintain the pads in contact with water at the boiling point for a substantial period of time. Heretofore in the case of sterilizers employing hot liquid contact, a difiicult problem has been encountered in providing satisfactory means for wringing or otherwise driving excess liquid from the pads to prepare them for use without recontaminating the pads and vitiating the sterilization thereof. The apparatus of this invention, when operated in the manner contemplated, obviates this difiiculty.

In operation, dry pads 22, covered by the follower plate I3, are placed as shown in Fig. 1. Heat is supplied through the element 6 until the liquid boils. When this occurs liquid is driven up into the basin 9, completely immersing the pads 22. The liquid, furthermore, continues to rise through the clearance between the follower plate I3 and side walls into the space I9 to a level substantially above the follower plate I3. During this action the liquid level falls in the boiler compartment to and slightly below the lower end of the dip pipe I2 and steam passes up the dip pipe to maintain the contents of the basin 9 at boiling temperature. The maintenance of boiling temperature in the basin is further facilitated by heat transfer through the relatively thin sheet metal head I0, without which it would be difficult to maintain sterilizing temperatures.

sterilizing conditions are thus maintained by continued supply of heat through element 6 until the period for effective sterilization is completed. Heating is then discontinued, whereupon loss of heat through radiation and convection, brings about condensation within the boiler compartment I, and this causes the liquid in the sterilizer 9 to begin to descend. The descent is at first gradual, but as soon as a small amount of the cooled fluid from above reaches the boiler compartment, a very marked reduction in pressure in the boiler compartment takes place and the liquid above tends to be quite forceably driven back into the boiler compartment I. Passage of liquid from above the plate l3, however, is restricted by the small clearance between the edges of the plate I3 and the side walls I4 of the basin 9. As a result, the pressure below is much less than the pressure above the plate I3 and the pads 22 become forcibly com-pressed, as indicated in Fig. 2. In this way liquid is effectively wrung from the pads 22 and when the last of the liquid is sucked from the basin 9 into the boiler compartment I, the pads are in the proper condition for immediate use.

If the pads are not to be used immediately, they may be maintained in hot, useable condition by reconnecting the heating element 6 and by opening the cock 23. In this way live steam is caused to pass into the basin 9, keeping the pads 22 hot and moist. The quantity of liquid normally held within the boiler compartment 1 is sufficient to permit a very considerable period of steaming in this fashion. If desired, the basin 9 may be covered by a lid, not shown, to render such steaming more effective.

This invention has been herein described by reference to a specific embodiment thereof. It is intended, however, that the protection of Letters Patent to be afiorded hereby be not unnecessarily limited thereby and that such protection extend to the full limit of the inventive advance disclosed herein, as defined by the claims hereto appended.

What I claim as my invention is:

1. In an apparatus for sterilizing pads in the nature of fibrous surgical pads by contact with hot liquid and for expelling said liquid therefrom after sterilization, the combination comprising a parallel-sided sterilizer basin for accommodating pads to be sterilized, a pad-covering follower-plate positioned in said basin transversely with respect to said parallel sides and movable longitudinally with respect thereto, said plate having a configuration closely approximating the configuration of a transverse section of said basin whereby a small clearance exists between the periphery of said plate and the walls of said basin, a boiler beneath said basin comprising an enclosure adapted to receive and contain liquid and vapor, an access opening in said boiler disposed at a level substantially below the top of said boiler and adapted to form with said boiler thesole means of ingress and egress therefor, and a pipe extending from said opening upwardly into communication with a lower part of said basin whereby changes in vapor pressure within said boiler to and from pressures above and below atmospheric pressure cause liquid above said access opening to be expelled from said boiler into said basin and tobe drawn back into said boiler without escape from said boiler of vapor above said opening.

2. In an apparatus for sterilizing pads in the nature of fibrous surgical pads by contact with hot liquid and for expelling said liquid therefrom after sterilization, the combination comprising a sterilizer basin for accommodating pads to be sterilized, a movable pad-covering follower-plate positioned in said basin, said follower-plate and said basin cooperating to form a passage for permitting fluid to pass from beneath said followerplate to above said follower-plate and to return therefrom at a restricted rate, a boiler beneath said basin comprising an enclosure adapted to receive and contain liquid and vapor, an access opening in said boiler disposed at a level substantially below the top of said boiler and adapted to form with said boiler the sole means of ingress and egress therefor, and a pipe extending from said opening upwardly into communication with a lower part of said basin whereby changes in vapor pressure within said boiler to and from pressures above and below atmospheric pressure cause liquid above said access opening to be expelled from said boiler into said basin and to be drawn back into said boiler without escape from said boiler of vapor abovesaid opening.

3. In an apparatus for sterilizing pads in the nature of fibrous surgical pads by contact with hot liquid and for expelling said liquid therefrom after sterilization, the combination comprising a vertical-sided enclosure having a tight bottom, an intermediate sheet tightly engaging said walls dividing said enclosure into a lower boilerportion and an upper sterilizer basin portion, a dip-pipe.

secured to said intermediate sheet communicating with said basin portion and extendin downwardly into the lower part of said boiler portion, heating means for said boiler, and a freely movable pad-covering follower-plate horizontally disposed in said sterilizer basin, said follow-plate being of such dimension as to closely approach the vertical walls of said sterilizer basin to provide a restricted peripheral clearance between said plate and said basin walls.

4. In an apparatus for sterilizing pads in the nature of fibrous surgical pads by contact with hot liquid and for expelling said liquid therefrom after sterilization, the combination comprising a sterilizer basin for accommodating pads to be sterilized, a boiler, a common heat-conducting partition wall between said boiler and said basin, means for heating liquid contained in said boiler, said boiler comprising an enclosure adapted to receive and contain liquid and vapor, an access opening in said boiler disposed at a level substantially below the top of said boiler and adapted to,

form with said boiler the sole means of ingress and egress therefor, and a pipe extending from into said boiler without escape from said boiler of vapor above said opening.

'5. In an apparatus for sterilizing pads in the nature of fibrous surgical pads by contact with hot liquid and for expelling said liquid therefrom after sterilization, the combinationcomprising a sterilizer basin for accommodating pads to be sterilized, a boiler positioned below said basin, a

dip-pipe in communication with said basin extending into said boiler to a low position in said boiler, a freely movable, close-fitting pad-cover slidably positioned within said basin, means for supplying heat to said boiler, a passage connecting the upper vapor space of said boiler with said basin, and a valve located in said passage for opening and closing the same.

FREDERICK MASON MINER, JR. 

